Hydrocarbon resins and hydrocarbon elastomers obtained from unsaturated aromatic hydrocarbons, namely from aromatic olefins or from fractions containing such aromatic olefins, have been used as modifiers for coatings, adhesives, rubbers, and IC encapsulants as they are capable of plasticizing base polymers, relaxing the internal stress generated during the curing of base polymers, increasing the initial tack and adhesive strength of base polymers, and improving the water resistance of base polymers. The modifying effects produced by such hydrocarbon resins and hydrocarbon elastomers, however, have not been too satisfactory. In particular, they are not applicable to strongly polar base polymers because of their poor compatibility. Moreover, they exhibit such low reactivity with base polymers as to reduce the mechanical strength, cohesion, adhesion, and rust-preventing capability of the base polymers after the curing of the coatings or adhesives or they migrate to the surface of the coatings or into the adhesive interface with the resultant discoloration and stickiness.
A few concrete examples are cited. In the preparation of corrosion-resistant lacquer compositions from polymers of acrylic acid or methacrylic acid or from copolymers of these acids with styrene, there have not been suitable substances which are reactive with these base polymers, function as plasticizers with good compatibility, and provide adhesion and rust prevention.
Two-pack epoxy or polyurethane coatings, adhesives, sealants, and caulking materials generate a large internal stress in the curing reaction and this disadvantageously reduces the adhesion, water resistance, and corrosion prevention of the cured coats or adhesive layers.
In the rubber industry, there has been a desire to apply a compound of natural rubber and a vinyl chloride resin to shoe soles and the like as a novel rubber having concurrently the elasticity of the former and the weathering resistance of the latter though the two constitute an incompatible system. Consequently, it has become necessary to find compatibilizers for such incompatible polymers. Known hydrocarbon resins, however tried, would not work as compatibilizers or tackifiers on account of their being compatible solely with the natural rubber phase.
In the automotive paints, there has arisen a need for improving the anti-corrosion performance of cationic electrodeposition coatings to be used for undercoats. The conventional hydrocarbon resins, however, are inert to cationic electrodeposition and are not applicable as anti-corrosion agents.
In the area of epoxy resin-based IC encapsulants, a large internal stress is generated during the curing of the encapsulants and this has caused a number of problems such as decreases in encapsulant-lead adhesion, water resistance, and reliabilty of the IC performance and formation of cracks. Hydrocarbon elastomers, for instance polybutene, have been applied to reduce the internal stress, but their poor compatibility with epoxy resins has produced such defects as staining of the molds during the molding operation, haze and turbidity on the surface of the molded articles, and bleeding to the surface.
Typical curing agents for epoxy resins are acid anhydrides, aromatic amines, and phenolic novolak resins. In particular, those epoxy resin molding materials which contain phenolic novolak curing agents have been used widely as encapsulants for IC and other semiconductor devices on account of their ease of molding, excellent moisture resistance, nontoxicity, and low cost.
A composition of epoxy resins and the resins obtained by polymerizing hydrocarbons such as styrene, indene, and alkylindenes and phenols in the presence of a Friedel-Crafts catalyst is disclosed in Japan Tokkyo Kokai Koho No. 59-52,656 (1984). The composition in question, however, is merely a mixture of individual resins and is not concerned with epoxidized hydrocarbon resins.
The present inventors have reviewed the prior art technology, conducted extensive studies, and completed this invention based on the finding that epoxy-modified hydrocarbon resins can be obtained by the copolymerization of hydrocarbon olefins and phenols in the presence of an acid catalyst followed by the reaction of the resulting copolymers with epichlorohydrin.
Accordingly, an object of this invention is to solve the problems in the conventional hydrocarbon resins and hydrocarbon elastomers.
Another object of this invention is to synthesize epoxy-modified hydrocarbon resins having the epoxy groups as reactive or polar functional group and offer such epoxy-modified hydrocarbon resins as modifiers or base polymers for coatings, adhesives, rubbers, and IC encapsulants.
Still another object of this invention is to provide epoxy-modified hydrocarbon resins which are useful as raw materials for the reactions with other substances having functional groups or chemical compositions reactive with the epoxy groups to furnish novel resins having simultaneously the functions inherent in the hydrocarbon resins and those in said other substances.